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Chemical, structural, and thermal properties of recovered nematic Liquid Crystal (LC) mixtures were investigated by applying several analytical techniques. A large quantity (65,700) of End-Of-Life (EOL) Liquid Crystal Display (LCD) screens were used to extract these LC blends. The studied EOL-LCD screens were heterogeneous in nature, particularly due to their different brands, production years, and dimensions. The collected TV and computer screens, as well as tablets, presented an average diagonal size of 24 inches. Chemical characterization revealed that the recovered compounds present typical chemical structures of LC molecules by the simultaneous presence of aliphatic chains and aromatic and polar groups. POM observations of these samples exhibited Schlieren and marble-like textures at room temperature, which are typical of nematic LCs. Moreover, thermal characterization and thermo-optical analysis showed that these LC mixtures displayed a broad nematic phase between −90 °C and +70 °C. [ABSTRACT FROM AUTHOR]

Research into broadwidth broadening for light reflections in polymer-stabilized cholesteric liquid crystal is described.

Due to the existence of a macroscopic helical structure, oriented cholesteric liquid crystals (CLCs) can selectively reflect light. The wavelength bandwidth for these Bragg reflections is limited: typically a few tens of nanometers due to limited birefringence values available in organic mesomorphic compounds. Here, we show that larger bandwidths may be reached by associating two layers of polymer-stabilized CLCs (PSCLCs). In the case of near-IR spectrum, it is shown that the optical properties of the bilayer system are not the sum of the individual properties. Time stability is investigated because the very existence of an interdiffusion between soft matter layers. Optical characteristics of the PSCLC can be tuned by an electric field and transitions between broadband reflecting, scattering, and transparent states are possible. For applications, switchable broadband reflections in liquid concentration media are relevant for white-or-black polarizer-free flat displays and "smart" windows in buildings. c 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]